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Named By: Charles Doolittle Walcott in 1911
Time Period: Cambrian, 520-505 Ma
Location: Worldwide distribution, but particularly well-known from Canada, British Columbia - Burgess shale. Also, China - Kaili Formation, Australia - Emu Bay Shale, Czech Republic - Buchava Formation
Size: Varying sizes from 3.4 to 50.8 millimetres
Diet: Bottom feeder
Fossil(s): Hundreds of known specimens, but sometimes only the spines are recovered
Classification: | Animalia | Lophotrochozoa |

Wiwaxia is a genus of soft-bodied animals that were covered in carbonaceous scales and spines. Wiwaxia fossils - mainly isolated scales, but sometimes complete, articulated fossils - are known from early Cambrian and middle Cambrian fossil deposits across the globe. The living animal would have measured up to 5 cm (2 inch) when fully grown, although a range of juvenile specimens are known, the smallest being 2 millimetres (0.079 in) long.

Wiwaxia's affinity has been a matter of debate: researchers were long split between two possibilities. On the one hand, its rows of scales looked superficially similar to certain scale worms (annelids); conversely, its mouthparts and general morphology suggested a relationship to the shell-less molluscs. More recently, evidence for a molluscan affinity has been accumulating, based on new details of Wiwaxia's mouthparts, scales, and growth history.

The proposed clade Halwaxiida contains Wiwaxia as well as several similar Cambrian animals.

Read more about Wiwaxia at Wikipedia
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